Refilling of a vehicle fuel tank is an integral procedure for a vehicle that is powered at least in part by an engine configured to propel the vehicle via combustion of fuel. However, refilling the vehicle fuel tank can be a time consuming and cumbersome activity for a vehicle operator. For example, time spent driving to and from a gas station, in addition to time spent refueling a vehicle and/or waiting at the gas station for an opportunity to refuel, can take away from time spent on other more desirable activities. In other examples, the act of refueling a vehicle may in itself not be desirable to certain vehicle operators, for one reason or another. As such, there are now examples of companies striving to reduce the negative aspects of vehicle refueling, by providing a service that delivers fuel on demand to a vehicle, regardless of where the vehicle may be located. However, current methods for such services require that the fuel door be unlocked. While some fuel doors do not lock, or may be opened by mechanical means such as pushing on the fuel door, fuel doors that must be unlocked can be potentially problematic to such a service if the customer is not physically present at the vehicle location but desires the vehicle to be fueled by the refueling service. Such a problem is especially true for plug-in hybrid electric vehicles (PHEVs), where the fuel tank is typically sealed except during refueling operations and wherein the fuel tank must be depressurized before the refueling door unlocks to allow refueling to commence. The inventors herein have recognized these issues.
Furthermore, a remote refueling event may comprise a desirable opportunity for conducting evaporative emissions test diagnostic procedures and/or diagnosing components in a vehicle evaporative emissions system and fuel system subsequent to the remote refueling event. More specifically, because a refueling event may result in agitation of fuel in the fuel tank and may thus increase fuel vaporization and fuel temperature, if the evaporative emission system and fuel system are sealed subsequent to the refueling event, a pressure increase above a predetermined threshold (or thresholds) may be indicative of an absence of undesired evaporative emissions. However, if the car were to be immediately driven subsequent to the refueling event, interpretation of the results of an evaporative emissions test diagnostic may be confounded by variables such as slosh in the fuel tank, change in fuel tank pressure resulting from the fuel pump removing fuel from the fuel tank, etc.
Still further, for vehicles with sealed fuel tanks, the tank is typically sealed via a fuel tank isolation valve (FTIV) positioned between the fuel tank and a fuel vapor storage canister. Diagnosing functionality of the FTIV may be readily accomplished in vehicles with an onboard pump configured to evacuated or pressurize the fuel tank. For example, the FTIV may be closed, and the onboard pump activated. If a pressure change is observed in the fuel tank, for example, then it may be indicated that the FTIV is not functioning as desired. Similarly, engine manifold vacuum may be used to conduct a similar diagnostic of the FTIV. However, some vehicles are not equipped with an onboard pump, and furthermore, some vehicles may operate primarily in electric-only mode, thus reducing any opportunities to rationalize the FTIV via the use of engine intake manifold vacuum. In such examples, another method of FTIV diagnosis is desirable, such that overloading of the fuel vapor storage canister may be prevented, which may thus reduce undesired evaporative emissions.
The inventors herein have recognized these issues, and have developed systems and methods to at least partially address them. In one example, a method is provided, comprising after refueling a fuel system that supplies fuel to an engine, sealing the fuel system, and an evaporative emissions system removably coupled thereto, from atmosphere and from each other, and while the fuel system and the evaporative emissions system remain sealed and the engine is off, testing each of the systems based on a first pressure change in the fuel system, and a second pressure change in the evaporative emissions system.
In one example, testing each of the systems further comprises indicating an absence of undesired evaporative emissions in the fuel system responsive to the first pressure change in the fuel system reaching a first predetermined pressure threshold that is positive with respect to atmospheric pressure, and indicating an absence of undesired evaporative emissions in the evaporative emissions system responsive to the second pressure change in the evaporative emissions system reaching a second predetermined pressure threshold that is negative with respect to atmospheric pressure.
In another example, sealing the fuel system and evaporative emissions system from each other is accomplished via a fuel tank isolation valve positioned in a conduit between the fuel system and evaporative emissions system. In such an example, the fuel tank isolation valve may be indicated to be not functioning as desired responsive to pressure in the fuel system and the evaporative emissions system converging to a common pressure while the fuel system and evaporative emissions system are sealed from each other and from atmosphere. In this way, both a fuel system and evaporative emissions system may be simultaneously tested for undesired evaporative emissions, and a fuel tank isolation valve may further be indicated as to whether it is functioning as desired. By testing the fuel system and evaporative emissions system as such, potential locations of undesired evaporative emissions may be determined, thus decreasing costs associated with mitigation, and may reduce undesired evaporative emissions released to atmosphere.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.